A server or an area on a server, commonly referred to as a realm, that requires authentication.
UIKit for Mac 13.0+Beta
A protection space defines a series of matching constraints that determine which credential should be provided. For example, if a request provides your delegate with an NSURLAuthenticationChallenge object that requests a client username and password, your app should provide the correct username and password for the particular host, port, protocol, and realm, as specified in the challenge’s protection space.
This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.